Results of the EWS simulation (left) and of the EDS simulation (right) comparing the measured extracted versus incident H band magnitudes calculated in the AB system. The magnitude is obtained convolving the extracted and incident spectra with the transmission curve of the Η_Έ filter on the mutual wavelength range between the RGS passband and Η_Έ. The scattered circles are corrected for the estimated loss due to the aperture (see Sect. 5.1.3). The sources are colour-coded with the S/N, as shown by the right-side colour bar, and the grey circles are objects with S/N < 3.5. The black diagonal line shows the 1:1 ratio. The contours are the iso-proportions of the distribution density of our measurement, starting at 20% with a 10% step, before applying the correction due to the aperture loss.